74 11.2 Naming Skeletal Muscles

Learning Objectives

Explain how understanding the muscle names helps describe shapes, location, and actions of various muscles

The Greeks and Romans conducted the first studies done on the human body in Western culture. The educated class of subsequent societies studied Latin and Greek, and therefore the early pioneers of anatomy continued to apply Latin and Greek terminology or roots when they named the skeletal muscles. The large number of muscles in the body and unfamiliar words can make learning the names of the muscles in the body seem daunting, but understanding the etymology can help. Etymology is the study of how the root of a particular word entered a language and how the use of the word evolved over time. Taking the time to learn the root of the words is crucial to understanding the vocabulary of anatomy and physiology. When you understand the names of muscles it will help you remember where the muscles are located and what they do (Figure 1, Figure 2, and Table 2). Pronunciation of words and terms will take a bit of time to master, but after you have some basic information; the correct names and pronunciations will become easier.

Figure 1. Overview of the Muscular System. On the anterior and posterior views of the muscular system above, superficial muscles (those at the surface) are shown on the right side of the body while deep muscles (those underneath the superficial muscles) are shown on the left half of the body. For the legs, superficial muscles are shown in the anterior view while the posterior view shows both superficial and deep muscles.

Figure 2. Understanding a Muscle Name from the Latin

Mnemonic Device for Latin Roots (Table 2)

Example

Latin or Greek Translation

Mnemonic Device

ad

to; toward

ADvance toward your goal

ab

away from

n/a

sub

under

SUBmarines move under water.

ductor

something that moves

A conDUCTOR makes a train move.

anti

against

If you are antisocial, you are against engaging in social activities.

epi

on top of

n/a

apo

to the side of

n/a

longissimus

longest

“Longissimus” is longer than the word “long.”

longus

long

long

brevis

short

brief

maximus

large

max

medius

medium

“Medius” and “medium” both begin with “med.”

minimus

tiny; little

mini

rectus

straight

To RECTify a situation is to straighten it out.

multi

many

If something is MULTIcolored, it has many colors.

uni

one

A UNIcorn has one horn.

bi/di

two

If a ring is DIcast, it is made of two metals.

tri

three

TRIple the amount of money is three times as much.

quad

four

QUADruplets are four children born at one birth.

externus

outside

EXternal

internus

inside

INternal

Anatomists name the skeletal muscles according to a number of criteria, each of which describes the muscle in some way. These include naming the muscle after its shape, its size compared to other muscles in the area, its location in the body or the location of its attachments to the skeleton, how many origins it has, or its action.

The skeletal muscle’s anatomical location or its relationship to a particular bone often determines its name. For example, the frontalis muscle is located on top of the frontal bone of the skull. Similarly, the shapes of some muscles are very distinctive and the names, such as orbicularis, reflect the shape. For the buttocks, the size of the muscles influences the names: gluteus maximus (largest), gluteus medius (medium), and the gluteus minimus (smallest). Names were given to indicate length—brevis (short), longus (long)—and to identify position relative to the midline: lateralis (to the outside away from the midline), and medialis (toward the midline). The direction of the muscle fibers and fascicles are used to describe muscles relative to the midline, such as the rectus (straight) abdominis, or the oblique (at an angle) muscles of the abdomen.

Some muscle names indicate the number of muscles in a group. One example of this is the quadriceps, a group of four muscles located on the anterior (front) thigh. Other muscle names can provide information as to how many origins a particular muscle has, such as the biceps brachii. The prefix bi indicates that the muscle has two origins and tri indicates three origins.

The location of a muscle’s attachment can also appear in its name. When the name of a muscle is based on the attachments, the origin is always named first. For instance, the sternocleidomastoid muscle of the neck has a dual origin on the sternum (sterno) and clavicle (cleido), and it inserts on the mastoid process of the temporal bone. The last feature by which to name a muscle is its action. When muscles are named for the movement they produce, one can find action words in their name. Some examples are flexor (decreases the angle at the joint), extensor (increases the angle at the joint), abductor (moves the bone away from the midline), or adductor (moves the bone toward the midline).

Chapter Review

Muscle names are based on many characteristics. The location of a muscle in the body is important. Some muscles are named based on their size and location, such as the gluteal muscles of the buttocks. Other muscle names can indicate the location in the body or bones with which the muscle is associated, such as the tibialis anterior. The shapes of some muscles are distinctive; for example, the direction of the muscle fibers is used to describe muscles of the body midline. The origin and/or insertion can also be features used to name a muscle; examples are the biceps brachii, triceps brachii, and the pectoralis major.

Review Questions

1. The location of a muscle’s insertion and origin can determine ________.

action

the force of contraction

muscle name

the load a muscle can carry

2. Where is the temporalis muscle located?

on the forehead

in the neck

on the side of the head

on the chin

3. Which muscle name does not make sense?

extensor digitorum

gluteus minimus

biceps femoris

extensor minimus longus

4. Which of the following terms would be used in the name of a muscle that moves the leg away from the body?

flexor

adductor

extensor

abductor

Critical Thinking Questions

1. Describe the different criteria that contribute to how skeletal muscles are named.

Glossary

abductor

moves the bone away from the midline

adductor

moves the bone toward the midline

bi

two

brevis

short

extensor

muscle that increases the angle at the joint

flexor

muscle that decreases the angle at the joint

lateralis

to the outside

longus

long

maximus

largest

medialis

to the inside

medius

medium

minimus

smallest

oblique

at an angle

rectus

straight

tri

three

Solutions

Answers for Review Questions

A

C

D

C

Answers for Critical Thinking Questions

In anatomy and physiology, many word roots are Latin or Greek. Portions, or roots, of the word give us clues about the function, shape, action, or location of a muscle.